The present invention relates to an electronic musical instrument and, more particularly, to an electronic musical instrument which can simultaneously generate musical tones having a plurality of tone colors.
In some conventional electronic musical instruments, a keyboard is used as a pitch designating means, and pitches are sequentially designated by operating keys of the keyboard, thereby simultaneously generating musical tones having a plurality of pitches predetermined with respect to the pitches of the designated keys.
First, for example, tones having a tone color of an orchestra and those having a tone color of a flute are prepared. When a performer depresses a key, two musical tones having the same pitch as that of the depressed key or pitches offset from each other by an octave are generated, thereby generating a so-called ensemble effect in a performance tone.
Second, when a performer depresses keys, pitches of musical tones of the first tone group are changed in accordance with changes in pitches of sequentially-depressed keys. At the same time, pitches of musical tones of the second tone group are changed to have a predetermined pitch difference with respect to the musical tones of the first tone group, thereby generating a so-called duet effect in a performance tone.
However, in the conventional electronic musical instruments of this type, a pitch difference of musical tones simultaneously generated and having different tone colors is permanently determined with respect to the pitch of a depressed key. Therefore, a performance tone tends to be monotonous, resulting in insufficient musical expressions as an electronic musical instrument. This problem is serious in a music synthesizer, especially in a music synthesizer of wind instrument type because only one pitch can be designated in this synthesizer.
In addition, in the conventional electronic musical instruments, a pitch difference of a harmonic tone to be added to a melody tone is predetermined with respect to the melody tone. Therefore, an expression of a performance tone becomes insufficient.